Elastic O-rings are in widespread use as orthodontic devices for ligating an arch wire to an orthodontic bracket, and for applying corrective forces to teeth. These elastomeric rings are described in detail in U.S. Pat. No. 3,530,583 and U.S. Pat. No. 3,758,947, and they are typically made of a plastic material which is resistant to mouth fluids and able to maintain long-duration elasticity in the mouth environment. The rings are usually of toroidal or donut shape, but may be oval or otherwise configured, and the term O-ring is used herein to include all such shapes.
In common with almost all intraoral orthodontic appliances, the elastic rings are quite small, and in a typical size for ligation have an outside diameter of one-eighth inch or less, and an inside diameter of less than one-sixteenth inch. When first commercially introduced, these rings were supplied loose in bulk containers, and the orthodontist or assistant was forced to pick up an individual ring with the fingers or a forcep for alignment and subsequent placement in the mouth. This proved inconvenient, and rings were often dropped, or unwanted multiple rings might inadvertently be withdrawn from the bulk container.
This handling problem was partially solved by the development of an integrally molded assembly of many rings each joined by a frangible branch or neck to a central core which was conveniently handheld. An individual ring is gripped by a plier or forcep, and snapped off the core for realignment between the tips of the gripping tool and placement in the mouth. Various configurations of such as are disclosed in U.S. Pat. No. 4,038,753 and U.S. Pat. No. 4,217,686.
The molded assembly or O-ring "tree" is popular with orthodontists, but the problem remains of realigning the now-separated O-ring between the gripping-tool tips so the tips do not cover or obscure the ring central opening (the "hole in the donut"). This opening must remain clear so the ring can be installed (e.g., stretched and fitted over the tie wings of an orthodontic bracket when the ring is used to ligate an arch wire in place), and the tiny ring must be painstakingly repositioned between the tool tips or beaks to achieve the desired alignment.
This invention eliminates the time-consuming repositioning step by housing the O-rings in a case or dispenser which prevents the grasping-tool tips from passing over the ring central hole by exposing for gripping only a small annular portion of the ring. The tool tips are stopped by the dispenser in a fashion which prevents the tips from obscuring the ring opening, and the resulting automatic ring alignment eliminates the annoying repositioning procedure.